(a) Field of the Invention
The present invention relates to a power cable breaking detection method for an electric vehicle, a hybrid vehicle, a fuel cell vehicle and the like.
(b) Description of the Related Art
An electric vehicle, a hybrid vehicle, a fuel cell vehicle and so on may use a motor provided with a permanent magnet.
The motor is driven by phase current which is supplied from an inverter through a power cable, where the phase current is converted from DC voltage into 3-phase AC voltage according to a PWM (Pulse Width Modulation) signal of a controller.
If a power cable connecting an inverter and a motor is broken or in short circuit, the motor does not operate sufficiently and also, high voltage and high current may be supplied to the inverter, and thus the entire system may not function properly.
Also, a disconnection/short circuit in the power cable may induce an excessive pulsation torque so as to break elements mechanically connected to the motor.
In the conventional art of power cable breaking detection, a successive switching sequence is supplied to an inverter and each current phase (U, V and W) is detected, each current phase (U, V and W) is analyzed, and a broken cable is detected before driving a motor. As used herein, the terms “current phase” and “phase current” are used interchangeably.
However, a conventional power cable breaking detection method may not detect power cable breaking in driving conditions.
In another conventional power cable breaking detection method, since one phase of current flowing through a broken cable is zero regardless of switching of an inverter, the other 2 current phases may have considerable errors comparing a current command, so errors are detected in order to detect power cable breaking.
However, by using the conventional current control error method, such a method may display a malfunction of current control of an inverter or over current malfunction, and may not detect which phase is malfunctioning, so that it may not be possible to appropriately diagnose and address the malfunction.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.